1. Field of the invention
The invention concerns a plug adapted to be fixed by means of a hot melt adhesive into an opening in a plate such as an automobile body in order to seal the opening.
2. Description of the prior art
A known plug of this kind comprises a molded plastics material body and a bead of HOT MELT adhesive deposited on a peripheral surface of the body around a surface transverse to the peripheral surface. The body has a generally circular shape and comprises three similar snap-fastener blades each extending between an attachment end and a free end in an axial direction perpendicular to the peripheral surface and parallel to the transverse surface. The attachment end is at the same level as the peripheral surface, the transverse surface being interrupted at the locations of the blades. An insertion ramp is provided between the free end and a retaining lip, the snap-fastener blades being adapted so that the insertion ramp bears against the edge of the opening when the plug is placed thereon, to bend if pressure is applied to the plug to force it into the opening and to expand subsequently with the retaining lip facing a first side of the plate and the bead of adhesive facing a second side of the plate.
The snap-fastener blades provide temporary retention, permanent retention being provided by the hot melt adhesive: the plate is adapted to be heated, for example to set paint recently applied to it, whereupon the adhesive melts and when it has cooled the plug is welded to the plate, the opening being sealed.
The openings for which the plug is intended are usually stamped into the plate and therefore are subject to significant variations in size so that it may not be possible to force the plug into the opening or the blades may not be able retain it there.
The invention is directed to overcoming these drawbacks.